1. Field of the Invention
The present invention relates to an inkjet printing apparatus and an inkjet printing method both capable of suppressing drying of ink in an inkjet print head.
2. Description of the Related Art
Japanese Patent Laid-Open No . 2000-255053 discloses a technique used for a printer in which a plurality of inkjet print heads are arranged in a sheet conveyance direction, to feed humidified gas from an upstream side to the vicinity of nozzles in the print head to retain the humidity in the print head, thus suppressing drying of ink.
A sheet formed of a material such as paper has equilibrium moisture corresponding to humidity (the state in which the moisture in the sheet no longer changes). The sheet absorbs the moisture in the air when the humidity is high, and releases the moisture contained in the sheet when the humidity is low. When the sheet is fed to the vicinity of the print head with the humidity thereof increased by the fed humidified air, the sheet absorbs the moisture.
Thus, the humidity of the atmosphere may decease to prevent the humidity in the print head from being properly retained. In particular, if the print head includes a plurality of print heads arranged along a direction in which the humidified air is introduced, a long time is required for the humidified gas fed from the upstream side to reach a downstream side. In the meantime, when the sheet absorbs the moisture, downstream print heads are likely to fail to sufficiently retain humidity. The insufficient humidity retention may cause improper ink ejection or the like and thus degraded image quality.